Vitae philosophorum

Diogenes Laertius

Diogenes Laertius. Hicks, R. D., editor. Cambridge, MA.: Harvard University Press; London: William Heinemann Ltd., 1925.

For the presentations which, e.g., are received in a picture or arise in dreams, or from any other form of apprehension by the mind or by the other criteria of truth, would never have resembled what we call the real and true things, had it not been for certain actual things of the kind with which we come in contact. Error would not have occurred, if we had not experienced some other movement in ourselves, conjoined with, but distinct from,[*](διάληψιν ἔχειν,to be distinct; again,§ 58; so διαληπτόν, distinguishable (§ 57).) the perception of what is presented. And from this movement, if it be not confirmed or be contradicted, falsehood results; while, if it be confirmed or not contradicted, truth results.

And to this view we must closely adhere, if we are not to repudiate the criteria founded on the clear evidence of sense, nor again to throw all these things into confusion by maintaining falsehood as if it were truth.[*](Epicurus was a severe critic of the Sceptics; cf.§§ 146, 147; Frs. 252, 254 (Us.); Lucr. iv. 507-521.)

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Again, hearing takes place when a current passes from the object, whether person or thing, which emits voice or sound or noise, or produces the sensation of hearing in any way whatever. This current is broken up into homogeneous particles, which at the same time preserve a certain mutual connexion and a distinctive unity extending to the object which emitted them, and thus, for the most part, cause the perception in that case or, if not, merely indicate the presence of the external object.

For without the transmission from the object of a certain interconnexion of the parts no such sensation could arise. Therefore we must not suppose that the air itself is moulded into shape by the voice emitted or something similar[*](Air is not, as Democritus held (Beare, op. cit.p. 99), the medium, any more than for vision (§ 49). By something similar Epicurus probably means to include sound or noise. Lucretius treats of hearing in iv. 524-614, ii. 410-413.); for it is very far from being the case that the air is acted upon by it in this way. The blow which is struck in us when we utter a sound causes such a displacement of the particles as serves to produce a current resembling breath, and this displacement gives rise to the sensation of hearing.

Again, we must believe that smelling,[*](Cf. Lucr. iv. 673-705, ii. 414-417. Neither taste nor touch is treated separately in this epistle.) like hearing, would produce no sensation, were there not particles conveyed from the object which are of the proper sort for exciting the organ of smelling, some of one sort, some of another, some exciting it confusedly and strangely, others quietly and agreeably.

Moreover, we must hold that the atoms in fact possess none of the qualities belonging to things which come under our observation, except shape, weight, and size, and the properties necessarily conjoined

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with shape.[*](For shape cf. Lucr. ii. 333-521, iii. 185-202; for weight cf. Lucr. ii. 184-215, i. 358-367. For qualities generally cf. Epic. Frs. 288, 289 (Us.); Sext. Emp. Adv. math. ix. 335. Atoms have no colour (Frs. 29, 30, 289; Lucr. ii. 730-841), nor smell (Lucr. ii. 846-855) nor flavour nor sound nor cold nor heat (ib. 856-859), in short no variable quality (ib. 859-864); but the various qualities are due to the arrangement, positions, motions, and shape of the component atoms.) For every quality changes, but the atoms do not change, since, when the composite bodies are dissolved, there must needs be a permanent something, solid and indissoluble, left behind, which makes change possible: not changes into or from the non-existent, but often through differences of arrangement, and sometimes through additions and subtractions of the atoms.[*](If something unchanging underlies every change, the transformation of things and of their qualities must be due to the motion of the component atoms. With ἐν πολλοῖς understand στερεμνίοις: the arrangement of the atoms varies in solid objects.) Hence these somethings capable of being diversely arranged must be indestructible, exempt from change, but possessed each of its own distinctive mass [*](In § 53 ὄγκος was translated particle, since the context shows that a group of atoms analogous to a visible film is meant. But here each of the permanent somethings, i.e. the atoms, has its own mass (ὄγκος) and configuration.) and configuration. This must remain.

For in the case of changes of configuration within our experience the figure is supposed to be inherent when other qualities are stripped off, but the qualities are not supposed, like the shape which is left behind, to inhere in the subject of change, but to vanish altogether from the body. Thus, then, what is left behind is sufficient to account for the differences in composite bodies, since something at least must necessarily be left remaining and be immune from annihilation.

Again, you should not suppose that the atoms have any and every size, [*](The opinion of Democritus.)lest you be contradicted by facts; but differences of size must be admitted; for this addition renders the facts of feeling and sensation easier of explanation.

But to attribute any and

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every magnitude to the atoms does not help to explain the differences of quality in things; moreover, in that case atoms large enough to be seen ought to have reached us, which is never observed to occur; nor can we conceive how its occurrence should be possible, i.e. that an atom should become visible.[*](Cf. Lucr. iv. 110-128, i. 599-627, ii. 478-521. The first of these passages states that the atom is far below the ken of our senses and much smaller than the things which our eyes begin to be able to see.)

Besides, you must not suppose that there are parts unlimited in number, be they ever so small, in any finite body. Hence not only must we reject as impossible subdivision ad infinitum into smaller and smaller parts, lest we make all things too weak and, in our conceptions of the aggregates, be driven to pulverize the things that exist, i.e. the atoms, and annihilate[*](Admitting indivisible atoms, hard solid bodies can be explained; whereas, if atoms were soft and thus divisible ad infinitum, all things would be deprived of solidity (Lucr. i. 565-576). Just before Lucretius has argued that, if atoms did not set a limit to the division of things, production or reproduction would be impossible, since destruction is wrought more quickly than it is repaired, and endless future time could not undo the waste of endless past time. Possibly, however, Epicurus is thinking of an argument similar to that used by Lucretius in ii. 522-568—that a finite number of shapes implies and requires an infinity of atoms of each shape.) them; but in dealing with finite things we must also reject as impossible the progression ad infinitum by less and less increments.